1. Field of the Invention
The present invention relates to a feedthrough, in particular to a feed through which passes through a part of a housing, for example a battery cell housing, whereby the housing part has at least one opening through which at least one conductor, embedded in a glass- or glass ceramic material, is guided.
2. Description of the Related Art
Accumulators, preferably lithium-ion batteries are intended for various applications, for example for portable electronic equipment, cell phones, power tools and in particular electric vehicles. The batteries can replace traditional energy sources, for example lead-acid batteries, nickel-cadmium batteries or nickel-metal hydride batteries.
Lithium-ion batteries have been known for many years. In this regard we refer you to the “Handbook of Batteries, published by David Linden, 2nd Issue, McGrawhill, 1995, Chapters 36 and 39”.
Various aspects of lithium-ion batteries are described in a multitude of patents, for example, U.S. Pat. No. 961,672; U.S. Pat. No. 5,952,126; U.S. Pat. No. 5,900,183; U.S. Pat. No. 5,874,185; U.S. Pat. No. 5,849,434; U.S. Pat. No. 5,853,914; as well as U.S. Pat. No. 5,773,959.
Lithium-ion batteries, in particular for applications in the automobile industry generally feature a multitude of individual battery cells which are generally connected in-series. The in-series connected battery cells are usually combined into so-called battery packs and then into a battery module which is also referred to as a lithium-ion battery. Each individual battery cell has electrodes which are led out of a housing of the battery cell.
In particular in the use of lithium-ion batteries in the automobile industry, a multitude of problems such as corrosion resistance, stability in accidents or vibration resistance must be solved. An additional problem is the hermetic seal of the battery cells over an extended period of time. The hermetic seal may, for example, be compromised by leakage in the area of the electrodes of the battery cell or respectively the electrode feedthrough of the battery cell. Such leakages may be caused by temperature changes and alternating mechanical stresses, for example vibrations in the vehicle or aging of the synthetic material. A short-circuit or temperature change in the battery or respectively battery cell can lead to a reduced life span of the battery or the battery cell.
In order to ensure better stability in accidents, a housing for a lithium-ion battery is suggested, for example in DE 101 05 877 A1, whereby the housing includes a metal jacket which is open on both sides and which is sealed. The power connection, or respectively the electrodes, are insulated by plastic. A disadvantage of the plastic insulation is the limited temperature resistance, the limited mechanical stability, aging and the uncertain hermetic seal over the service life. The feedthroughs on the lithium-ion batteries according to the current state of the art are therefore not integrated hermetically sealed into the cover part of the Lithium-ion battery. Moreover, the electrodes are crimped and laser welded connecting components with additional insulators in the interior of the battery.
An additional problem with the lithium-ion batteries according to the current state of the art is that the battery cells occupy a large space and because of the high currents due to resistance losses, heat and temperature changes occur quickly.
An alkaline battery has become known from DE 27 33 948 A1 wherein an insulator, for example glass or ceramic, is joined directly by means of a fusion seal with a metal component. One of the metal parts is connected electrically with an anode of the alkaline battery and the other is connected electrically with a cathode of the alkaline battery. The metals used in DE 27 33 948 A1 are iron or steel. Light metals like aluminum are not described in DE 27 33 948 A1. Also, the sealing temperature of the glass or ceramic material is not cited in DE 27 33 948 A1. The alkaline battery described in DE 27 33 948 A1 is a battery with an alkaline electrolyte which, according to DE 27 33 948 A1 contains sodium hydroxide or potassium hydroxide. Lithium-ion batteries are not mentioned in DE 27 33 948 A1.
A method to produce asymmetrical organic carboxylic acid esters and to produce anhydrous organic electrolytes for alkali-ion batteries has become known from DE 698 04 378 T2, or respectively EP 0885 874 B1. Electrolytes for rechargeable lithium-ion cells are also described in DE 698 04 378 T2, or respectively EP 0 885 874 B1.
Materials for the cell pedestal which receives the through-connection are not described; only materials for the connecting pin which may consist of titanium, aluminum, a nickel alloy or stainless steel.
A radio frequency (RF) feedthrough with improved electrical efficiency is described in DE 699 23 805 T2 or respectively EP 0 954 045 B1. The feedthroughs known from EP 0 954 045 B1 are not glass-metal feedthroughs. Glass-metal feedthroughs which are provided immediately inside, for example, the metal wall of a packing are described in EP 0 954 045 B1 as being disadvantageous since RF-feedthroughs of this type, due to embrittlement of the glass, are not durable.
DE 690 230 71 T2, or respectively EP 0 412 655 B1, describes a glass-metal feedthrough for batteries or other electro-chemical cells, whereby glasses having an SiO2 content of approximately 45 weight-% are used and metals, in particular alloys, are being used which contain molybdenum and/or chromium and/or nickel. The use of light metals is also insufficiently addressed in DE 690 230 71 T2, as are sealing temperatures or bonding temperatures for the used glasses. According to DE 690 230 71 T2, or respectively EP 0 412 655 B1, the materials used for the pin-shaped conductor are alloys which contain molybdenum, niobium or tantalum.
A glass-metal feedthrough for lithium-ion batteries has become known from U.S. Pat. No. 7,687,200. According to U.S. Pat. No. 7,687,200 the housing was produced from high-grade steel and the pin-shaped conductor from platinum/iridium. The glass materials cited in U.S. Pat. No. 7,687,200 are glasses TA23 and CABAL-12. According to U.S. Pat. No. 5,015,530 these are CaO—MgO—Al2O3—B2O3 systems having sealing temperatures of 1025° C. or 800° C. Moreover, glass compositions for glass-metal feedthroughs for lithium batteries have become known from U.S. Pat. No. 5,015,530 which contain CaO, Al2O3, B2O3, SrO and BaO whose sealing temperatures are in the range of 650° C.-750° C. and which are therefore too high for use with light metals.
A feedthrough has become known from U.S. Pat. No. 4,841,101 wherein an essentially pin-shaped conductor is sealed into a metal ring with a glass material. The metal ring is then again inserted into an opening or bore in a housing and is joined material to material through welding, for example through interlocking of a welding ring. The metal ring consists of a metal which has essentially the same or similar thermal coefficient of expansion as the glass material in order to compensate for the high thermal coefficient of expansion of the aluminum of the battery housing. In the design variation described in U.S. Pat. No. 4,841,101 the length of the metal ring is always shorter than the bore or opening in the housing. No references are made in U.S. Pat. No. 4,841,101 to the glass compositions, neither is a special application described for the feedthrough, for example for batteries, in particular Lithium-ion accumulators.
What is needed in the art is a feedthrough which avoids the problems of the current state of the art, in particular resistance losses should be kept to a minimum and after installation of the feedthrough only a small building space should be claimed in the battery cell.